Research Of Short-Pulse Fiber Laser Based On Novel Two-Dimensional Materials

Ultra-fast pulsed fiber lasers have been extensively used in scientific research,medical treatment,device processing,biomedical research and even the military industry due to the low-cost,simple in structure,flexibility,and easy to commercialize.Saturable absorbers,as the core components of ultra-fast fiber lasers,have been focused and investigated widely.Graphene,carbon nanotubes,topological insulators?TIs?,antimonene,silicene,black phosphorus?BP?,and transition-metal dichalcogenides?TMDs?that have emerged and been extensively studied by researchers due to their superior photoelectric and nonlinear properties.Novel selenides such as SnSe₂ and WSe₂owns great potentials for research and applications because of their excellent photoelectric properties,nonlinear properties,ultra-fast relaxation time and wide absorption spectrum.The main research contents of this thesis are as follows:1.The development of ultra-fast fiber laser was introduced.The passive mode-locked fiber lasers based on saturable absorber were detailed.The generation of optical soliton and the characteristics of Kelly sidebands have been investigated.2.Two passive mode-locked fiber lasers have been achieved based on WSe₂nanosheets,which were prepared by chemical vapor deposition?CVD?and transferred to the fiber path cords end and cone of the tapered fiber.The parameters of the two fiber lasers have been compared and analyzed.A soliton mode-locked pulse output with a center wavelength of 1554.3 nm,a pulse width of 3.6 ns,and a repetition rate of 1.98MHz has been achieved.The maximum average power was 8.6 mW.By adjusting the polarization controller and pump power,the highest 278-order harmonic mode-locked output was obtained.3.A passively erbium-doped mode-locked fiber laser?EDFL?based on SnSe₂nanosheets saturable absorber?SA?has been reported.SnSe₂ nanosheets were prepared and characterized by SEM,TEM,XRD,and Raman spectra.The twin-detector technique system was used to test its nonlinear properties.And the result showed the prepared SnSe₂ nanosheets had a modulation depth?MD?of 20.67%and a saturable absorption intensity of 3.53 MW/cm².The central wavelength,pulse duration,and average output power were 1563.4 nm,276 ps,and 14.74 mW respectively,corresponding to a pulse repetition frequency of 15.03 MHz.Besides,the harmonic mode-locking?HML?pulsed trains were realized and analyzed,which indicated that SnSe₂ owned excellent saturable properties and great potentials to ultra-fast photonics.4.A tunable multi-wavelength Q-switched fiber laser has been demonstrated based on a tuning device,which were designed and prepared by graphene,poly-methyl methacrylate?PMMA?and taper fiber.Multi-wavelength tuning from 1551.2 nm to1564.6 nm with a tuning width of 13.4 nm could be realized.The maximum output power of the laser was 8.12 mW and the repetition rate was 29.01 kHz.